This invention relates generally to improvements in tool handles and related mounting structures and methods for connecting a tool handle to a tool head. More particularly, this invention relates to a handle mounting assembly and method for securely connecting the tool handle to the tool head in a manner permitting quick and easy handle removal and replacement.
A wide variety of hand tools are known in the art wherein a tool handle of selected length is mechanically attached to a tool head. In one typical geometry, one end of the tool handle is fitted into an eyehole or socket formed in the tool head, and mechanical locking means are provided for maintaining these components in assembled relation. In an alternative geometry, an elongated mounting tang on the tool head is press-fitted into a hole or socket formed in the end of a tool handle. In either configuration, the connection between the tool handle and the tool head is sometimes reinforced with screws, rivets, steel ferrules, and the like. In virtually all cases, the connection between the tool handle and tool head has been intended to be a permanent connection, with removal of the tool handle occurring only in the event of handle breakage or related failure of the head-handle connection.
In the past, the predominant material of choice used in tool handles has been wood. Although wooden tool handles are available in different quality grades, the useful life of wooden handles is inherently affected by various environmental factors such as weather and humidity, dry rot, termites, etc. In some hand tools such as pruning shears and the like, lightweight tubular steel handles are used in lieu of wood, wherein the hollow steel handles are typically connected in a permanent fashion to a tool head. While tubular steel handles avoid some of the disadvantages of wood, the structural integrity and strength of steel handles can be lost relatively easily in response to impact-caused dents formed in the handle structure. When that occurs, the steel handle or handles can bend or collapse relatively easily at the dent site, resulting in a need to remove and replace the damaged handle, or otherwise discard the tool.
In recent years, improved tool handles have been developed wherein a tool handle is constructed from a combination of reinforcing fibers cured within a resin composite material. These composite material handles beneficially exhibit high strength characteristics in a relatively lightweight and cost-efficient construction as described, for example, in U.S. Pat. No. 4,570,988 and copending U.S. Ser. No. 045,464, filed Apr. 8, 1993. In addition, the composite material is highly resistant to environmentally induced degradation or to impact-caused damage during tool use. Such composite material tool handles, however, still require connection means for mechanically interlocking the tool handle with the tool head.
In some hand tools, periodic removal and replacement of tool handles may be desirable for reasons other than replacement of a broken or damaged handle. For example, many hand tools such as pruning shears and hedge shears and the like include steel tool heads defining one or more sharpened cutting edges which may require periodic resharpening over the useful life of the tool. In many cases, the tool head must be returned to the manufacturer or to a professional for resharpening. In this case, it is desirable for the tool handle or handles to be removed from the tool head during resharpening, so that the tool handle or handles may be used with a second tool head, whereby work can continue without interruption.
In addition, the length of the tool handle or handles used with a particular hand tool can vary according to the task to be performed. In the example of pruning shears, relatively short handles in the range of about 12 to 18 inches are commonly used to provide adequate leverage to cut or trim small branches and the like. Larger vegetation such as tree limbs will normally require a hand tool with longer handles to provide sufficient cutting leverage. In the past, to meet these alternative requirements, multiple tools having handles of different lengths were necessary. A single tool head adapted for quick and easy connection to handles of different lengths has not been available.
The present invention provides an improved apparatus and method for connecting a tool handle to a tool head in a manner permitting quick and easy removal and replacement of the tool handle, wherein the connection is particularly adapted for use with a lightweight and high strength handle formed from fiber resin composite material.